# 质数的判断
# def is_prime(n):
#     """
#     to check if a number is prime or not
#     """
#     if n <= 2:
#         return False
#     for i in range(2, int(n**0.5) + 1):
#         if n % i == 0:
#             return False
#     return True
# print(is_prime(30))

